A known hydrogen production system for industrially producing hydrogen includes a reforming reactor in which a hydrocarbon-based material such as methanol or natural gas is reacted for reformation to turn into a reformed gas (containing hydrogen), and an adsorption/separation apparatus that removes by adsorption unnecessary components contained in the reformed gas to lead out a hydrogen-rich gas. Also, known methods of reformation adoptable in the reforming reactor of the hydrogen production system include a steam reforming process and a partial oxidation reforming process.
By the steam reforming process, hydrogen is generated from the hydrocarbon-based material and water through a steam reforming reaction, which is an endothermic reaction. For example, the steam reforming reaction of methanol can be expressed by the following thermochemical equation (1).CH3OH+H20=3H2+CO2−49.5 kJ   (1)
Since the steam reforming reaction is an endothermic reaction, the reforming reactor, to which the mixed material containing the hydrocarbon-based material and water is continuously supplied, has to be continuously heated in order to properly carry out the steam reforming reaction, when the steam reforming process is exclusively employed as the reforming method in the reforming reactor of the hydrogen production system. Besides, in the practical operation of the hydrogen production system based on the steam reformation, inside of the reforming reactor has to be preheated to a desired temperature when starting up the system (before supplying the mixed material to the reforming reactor) and the mixed material has to be heated to turn into high temperature vapor before being supplied to the reforming reactor, so that the reforming reaction of the mixed material supplied to the reforming reactor immediately takes place. Such hydrogen production system based on the steam reformation is disclosed, for example, in patent document 1 cited below. The hydrogen production system according to the patent document 1 utilizes combustion heat obtained by burning a fuel continuously supplied separately from outside the system (city gas) to keep heating the inside of the reforming reactor and the mixed material to be supplied thereto. However, the system that requires continuously burning the external fuel to keep heating the inside of the reforming reactor and the mixed material is inefficient and prone to incur an increase in hydrogen producing cost. Moreover, the hydrogen production system including the mechanism for burning the external fuel to keep heating the inside of the reforming reactor and the mixed material external fuel often overgrows in overall scale, which is undesirable.                Patent document 1: JP-A-H09-309703        
By the partial oxidation reforming process, hydrogen is generated from the hydrocarbon-based material through a partial oxidation reaction, which is an exothermic reaction. For example, the partial oxidation reaction of methanol can be expressed by the following thermochemical equation (2).CH3OH+½O2=2H2+CO2+192.5 kJ   (2)
Since the partial oxidation reaction is an exothermic reaction (not an endothermic reaction), the inside of the reforming reactor does not have to be continuously heated when carrying out the reforming reaction, when the partial oxidation reforming process is exclusively employed as the reforming method in the reforming reactor of the hydrogen production system. However, the partial oxidation reaction only offers considerably lower hydrogen generation efficiency than the steam reforming reaction. Accordingly, the hydrogen production system based on the partial oxidation reaction is undesirable from the viewpoint of the hydrogen production efficiency. Besides, since the partial oxidation reaction is an exothermic reaction, the hydrogen production system based on the partial oxidation reaction has to be equipped with a heat-removal mechanism that continuously removes heat from the inside of the hydrogen production system based on the partial oxidation reaction to maintain an appropriate reaction temperature in the hydrogen production system based on the partial oxidation reaction. The hydrogen production system based on the partial oxidation reaction which requires such heat-removal mechanism for the reforming reaction often overgrows in overall scale, which is undesirable.